Which of the following orders regarding ionisation energy is correct

Ionisation energy is the energy required to remove an electron from outer shell of an atom. Since, on moving from left to right in a period, size decreases, thus larger amount of energy is required to remove an electron, i.e., ionisation energy increases. Although, the size of O-atom is smaller as compared to N but the ionisation energy of N is higher. This is because in case of N, the electron is to be removed from stable half-filled 2p3 orbital. Thus, the order of ionisation energy is O < N < F or N > O > F.